In a medium saucepan combine 1 1/2-2 cups fresh or frozen Blackberries and 1/4 cup Water. Bring to a boil, reduce heat and simmer about 5 minutes until fruit is tender. Combine 1/4 cup Sugar and 2 Tbsp. Cornstarch and stir into fruit. Cook and stir over medium heat until mixture is thickened and bubbly. Cook and stir an additional 2 minutes, then set aside.

Preheat oven to 350 F. In a medium bowl combine 1 1/2 cups flour, 3/4 cups Sugar, 1/2 tsp. Baking Powder and 1/4 tsp. Baking Soda. Cut in 1/4 cup Butter until mixture is coarse. Make a well in the center, set aside.

In a small bowl combine 1 beaten Egg, 1/2 cup Buttermilk and 1/2 tsp. Vanilla. Add this mixture, all at once, to the flour mixture. Stir until just moistened, batter should be lumpy.

Spread half of the batter in an un-greased square baking pan. Spread fruit filling on top and drop remaining batter in small mounds on top of fruit filling.

In another small bowl, stir together 1/4 cup Flour and 1/4 Cup Sugar. Cut in 2 Tbsp. Butter until misture is coarse, sprinkle over coffee cake.